Impregnated press-roll for pulp and paper machines.



JUDSON A. DE GEW', OF MONTREAL, QUEBEC, CANADA.

IIVIPBEGNATED PRESS-ROLL FOR PULP AND PAPER MACHINES.

No Drawing.

To all whom it may concern:

Be it known that I, JUDsoN A. DE GEW, a citizen of the Dominion of Canada, and resident of the city of Montreal, in the Province of Quebec and Dominion of Canada, have invented certain new and useful Improvements in Impregnated Press-Rolls for Pulp and Paper Machines, of which the following is a full, clear, and exact description.

This invention relates to the manufacture or treatment of press rolls for pulp and paper machines, and particularly to the rapid seasoning by impregnation of the specially prepared wooden rolls suitable for use in wet places where special properties are required.

Wooden press rolls for paper mills as used to-day are always saturated with water, and the surface always has water adhering to it. When the web of wet paper meets the roll, it is pressed against it, leaving no air space between the wet roll and the wet pulp. Consequently, the paper is held firmly upon the roll both by adhesion and by external air pressure, and peels off with great difliculty. Furthermore, the fibers of the wet paper are peeled ofi the surface a few at a time, leaving the surface ragged and uneven, and thus injuring the character of the stock.

My invention is designed to overcome these difficulties by filling the pores of the wood with a water repellent material, which does not have any adhesive tendency toward the moist pulp, against which it comes in contact. I find, by thoroughly impregnat ing the wooden rolls with wax or oil, that the wood itself is rendered practically free from water, and all the exposed pores of the wood are filled with wax instead of water. As the surface of the roll wears, there will be a slight concavity in each pore of the wood where wax is present, but this material being water repellent will hold in the hollow or depression a small amount of air when the wet pulp is pressed against it. The air thus held in the surface depressions will prevent a vacuum being formed, and Wlll enable the wet pulp to fall from the roll with great ease. It is very desirable that the impregnating material should be softer and less wear resisting than the wood fiber, so that it will be forced into the small depressions, as described.

I desire to obtain, therefore, a woody Specification of Letters Patent.

Patented A11 7, 1917.

Application filed February 19, 1915. Serial No. 9,425.

product in which the cells are freed from moisture and impregnated with a Waxy product or composition, the natural moisture of the wood being replaced by the wax compound.

Myprocess of treatment is as follows The wooden rolls, while preferably in a green or unseasoned condition, are immersed in a bath of melted wax. On heating the contents of the bath to a temperature slightly above 212 Fahrenheit, or the boiling point of water, the moisture in the wood is expelled by ebullition or boiling, and the air is also driven off from the cells of the wood. In this manner, moisture can be removed from the wood product without producing checks or fractures in the wood, such as are formed by artificial drying in the air. It is possible by this means to remove all the moisture from a full cross section of a piece of timber without any injury to the timber itself, and it is well known that wood freed from moisture is thereby rendered harder and stronger than when in a wet condition. The immersed wood product treated in this way is then allowed to absorb the molten wax at a temperature slightly less than 212 Fahrenheit, and the wax is soaked into the pores of the wood by the vacuum created and replaces the air and moisture driven out.

Another method of treatment is to dry the wood by means of a vacuum, which would remove the air and moisture, and then to impregnate the wood with a molten wax solution by means of pressure. The essential steps in any case are first to remove the air and moisture from the wood by such means as will not injure the wood, and then to impregnate the mass with a waxy material, thus obtaining a woody product in which the cells freed from moisture are filled with the wax product. Instead of using wax, certain oils or compositions of oils and wax may be used, or any water repellent composition which will render the wood product hard, smooth and resistant in every way to moisture. Any suitable tank may be used and any suitable heating means may be applied to carry out the treatment, which treatment may be applied equally well to built up rolls as well as to natural wood.

As far as I am aware, press rolls for paper machines have never been treated in the manner above described, and it has been necessary to keep these rolls constantly submerged or soaked in Water to prevent checking. Many press rolls have been ruined on account of accidental drying When the rolls have been out of use. Furthermore, Wood which is saturated with Water is much softer and Wears much more easily than rolls treated by my process. The use of press rolls made in this Way Will be of great advantage to paper manufacturers as better and more uniform paper may be produced. The rolls may be exposed to the air at any time Without danger of injury by drying and furthermore, softer and less expensive material may be employed.

Having thus described my invention, What I claim is p 1. A press roll-for use on paper and pulp machines having its natural moisture removed and replaced by Waxy or Water repellent material.

2. A Wooden press roll having its fibrocellular material impregnated With Waxy or oily composition.

In Witness whereof, I have hereunto set my hand, in the presence of two Witnesses.

JUDSON A. DE OEVV.

Witnesses:

C. W. TAYLOR, G. M. MORELAND.

Copies of this patent may be obtained for five cents each, by addressing the tiommissioner of Patents,

Washington, D. G. V 

